The film tells the true story of how Bulgar, the brother of a state senator (Benedict Cumberbatch), became one of the most infamous and violent gangsters in the history of South Boston, maybe even the United States. It also delves into when he became an FBI informant and took down a mafia family that was invading his turf.

Depp and Cumberbatch aren't the only big names in this movie. Joel Edgerton, Kevin Bacon, Adam Scott, Dakota Johnson, Juno Temple, Cory Stoll and Peter Sarsgaard also among the cast.

The soundtrack to Black Mass promises to be just as good as the movie. The trailer is set to Yelawolf's song "Till It's Gone," and makes the scenes all the more intense.